The spread of defined contribution pension plans and the possibility of individual accounts for Social Security make financial security in retirement ever more likely to depend on good asset allocation and portfolio choices. The HRS provides unparalleled data not only on portfolio behavior, but also on a wide range of things that might influence portfolio behavior?both those that are featured in traditional economic theories of portfolio choice (such as risk tolerance and rate of return expectations) and those that behavioral economists suggest might matter despite being absent from traditional theories. The aim of this project is to identify what, in fact, governs cross-sectional difference in portfolio choice. Identifying the factors that govern portfolio choice will help us determine whether people's financial investment decisions can be improved in order to provide for greater financial security toward the end of life.